Aerial extension ladder



Jan. 31, 1956 Original Filed Sept. 28,

E. J. ARPS 2,732,992

I AERIAL EXTENSION LADDER 4 Sheets$heet 1 fwevzhr W ail/1776 Jan. 31,1956 E. J. ARPS AERIAL EXTENSION LADDER Origmal Filed Sept. 28, 1946 4Sheets-Sheet 2 E] I w l lvwerziar 12am Jflrizs Jan. 31, 1956 E. J. ARPS2,732,992

AERIAL EXTENSION LADDER Original Filed Sept. 28, 1946 4 Sheets-Sheet 3Jan. 31, 1956 E. J. ARPS AERIAL EXTENSION LADDER 4 Sheets-Sheet 4[Weider [far/Wad J19 1705 Wharf way between its side rails;

AERIAL EXTENSION LADDER Edmund J. Arps, Oshkosh, Wisl, assignor to MaximMotor Company, Middleboro, Mass, a corporation of Massachusetts 13Claims. 01.. 228-9) This invention relates to aerial ladders for fireapparatus and more especially to extension ladders and their operation.

' Heretofore, extension and retraction of sections of aerial laddershave been effected by cables placed about pulleys carried by thesesections, the cable being taken u'p'and let out by a winch located atthe'base of the ladder and in other instances a piston and cylinderassembly has been employed in which the stroke of the piston wasdepended upon to take up or let out sufficient'cable to effect necessaryextension and retraction of the ladder sections. The chief disadvantagesof the foregoing are the excessive space requirement to accommodate themechanism, the comparatively slow speed of extension and retraction andthe pronounced tendency for bowing-of the ladder sections which if notcompensated for by increasing the sectionmodulus or by extensivereinforcement causes binding so that the sections will not slide freely.

' The principal objects of this invention are to provide for compactnesswithout sacrificing in any degree the amount of extension which may beobtained, to minimize bowing of the sections as they are extended andretracted without increasing the section modulus of the side rails ofthe ladder sections or adding stiffening or reinforcing members andhence to insure ease of sliding movement of the section and to providefor rapid extension and retraction. i

As herein illustrated a plurality of ladder sections are sl'idablyconnected to each other so as to slide one upon the other from aretracted position in which they are superposed to an extended positionin which they are substantially end to end, a minimum overlap at theends when extended of course being maintained to insure rigidity.Extension and retraction is effected by a cable system, control of whichis effected by a power cylinder,

. the latter being mounted on the lowermost ladder. section at its basesoas robe contained within the cable system. The power cylinder has apiston rod movable in its stroke parallel to the plane of the sectionand substantially mid- The cable system is connected to the piston rodfor effecting extension and retraction of the ladder sections-andincludes pulleys fast to the ladder sections carrying lengths of cablefor multiplying the stroke of the piston rod and lengths of cable fortransmitting the multiplied motion to the laddersections. Themultiplying lengths ofthe cable are mounted on multiple sheave pulleyblocks, two of which are mounted on the lowermost ladder section andanother of which is mounted on the piston rod and is located between thetwo so that extension of the piston extends the sections and retractionof the piston rod produces the opposite effect. The sheaves carryingthe, motion transmitting lengths of cable are connected to the laddersections in such positions that the motion transmitting portion of thecable lies at. opposite sides of the. -plane of the sections and hencethe runs of the cable exert equal. and opposite pulls on. any givensection andon the overall extended sections thereby eliminating anybinding of the sections. The cable is so arranged as to multiply thestroke of the piston rod in the ratio of approximately 7 to 1. The powercylinder is located substantially in the plane of the lowermost laddersection and moves therewith so that regardless of the angular positionof theladder the pull exerted by the piston on the cable system isalways in the same plane.

The invention will now be described in greater detail with reference tothe accompanying drawings wherein:

Fig. 1 is a plan view of the turntable of a fire apparatus showing anaerial ladder'in collapsed or retracted position and depressed so as. tobe substantially horizontal;

Fig. 2 is a side elevation of the turntable showing the ladderina'depressed' position in full lines and partially elevated in dottedlines; p

' Fig. 3 is a vertical section transversely of the ladder sections whentelescoped at the left side of, the multiplesheave pulley block near theuppr ends of the lowermost ladder section to m'u'chlarger scale showingthe details of the ladder sections themselves and the pulley-mountmgs;Fig. 3a is afragm'entary" side View partly in section showing meansforfastening the multiple-sheave pulley at the lower end of thelowermost ladder section and the end of the cable to the ladder sectionrather than to the cylinder; and

Fig. 3b is a plan view of a fragmentary part of the uppermost laddersection showing an alternativeanchorage for the extension cable fastenedthereto.

Fig. 4 is a plan view of the ladder sections displaced laterally to showthe path of the cable system.

Referring to the drawings, Figs. 1 and 2, there is shown a aerial ladder10 mounted on a turntable 12 which in turn is mounted on a chassis 14 ofa motor vehicle. The turntable 12 is supported for turning movement onthe chassis by a platform base 16 made fast to the chassis. On theplatform base 16 there is fastened a ring lhhaving on its outerperiphery gear teeth 20 and on its inner periphery a horizontal,inwardly extending lip 22. A ring 24 is made fast to theunderside of thetable and a ring 25 is fastened to the ring 24, the combined ringshaving in their opposingfaces annular ways which together form anexternally located groove 27 for the reception of the lip 22. There'aregroovesin the lip and in the walls of the groove 27 for receiving ballbearings 26 so that the table may turn on the base with the minimumamount of friction.- Rotation of the table is effected as will appear byreference to my Patent No. 2,614,743, by a gear mounted on the undersideof the table which meshes with-the gear 20 which is driven by hydraulicmeans including a pump P mounted on the. top of the table at the centerof rotation thereof. The pump P is connected by a vertical shaft 28including a suitable coupling to a gear reduction unit 30 fastened tothe chassis 14 and this in turn is connected by a suitable coupling andshafts to a take off from the drive shaft of the motor vehicle. Theforegoing pump P as appears in the application referred to abovesupplies hydraulic fluid under pressure to cylinders for raising andlowering the ladders and for effecting extension and retraction thereof.Valve and valve operating means V and C provide for control of the flowof fluid under pressure to the motor cylinders.

The extension ladder 10 consists of three sections S1, S2 and S3 and ispivotally mounted on the table 12 so as to be raised from asubstantially horizontal position through approximately to a nearlyvertical position, the angle of elevation at any given time dependingupon the particular conditions to be met. To this end there is madefasttothe table'spaced support members 34-34. The lower end of. thelowermost ladder section S1 has fast toj'it' bracketlmemb'ers 38-38which. are inclined to the ladder section as shown in Fig. Z'and theseare pivotally secured to the members 3434 at 36-36. Each section hasfastened to it handrails 52, the rails on the lower section being shownin .dot and dash lines since the details of this structure are notnecessary to a complete understanding of the invention.

The lowermost ladder section SI (Fig. 3) consists of spaced parallelside rails 3939 between which are fastened longitudinally spaced rungs40 of tubular cross section. Each rung is fastened at its opposite endsto the side rails 3939 by shafts 42 and nuts 44. A bushing 46 surroundsthe inner end of each shaft 42, the bushing fitting into the open endofthe rung and has a flange 47 at its outer end of substantially the samediameter as the rung. A bushing 48 is inserted through an opening ineach side rail 38 so as to surround the shaft 42 and has a flange 49 atits inner end. Between the flanges 47 and 49 of the bushings 46 and 48there is mounted on the shaft 42 a roller 50 and this as illustrated isadapted to receive the lower part of the side rail of the ladder sectionS2 which is mounted on the section S1 for reducing the frictionalengagement of the sections as they slide on each other. The laddersection S2 corresponds in structure to that of the ladder section S1having side rails 56-56 joined by rungs 58. Shafts 60 are provided forjoining the rungs to the side rails and since they are substantiallyidentical except for the fact that this section S2 is slightly smallerin width than the section S1 a further description is not deemednecessary. The ladder section S3 rests on the rollers of the section S2,is of narrower width and of somewhat different construction in that therungs 64 are welded directly to the side rails 62--62.

The ladder sections S1, S2 and S3 are elevated and depressed as a unitby a pair of piston and cylinder assemblies 66 (Figs. 1 and 2) each ofwhich consists of a power cylinder 68 and a piston to Which there isfast a piston rod 74. A bar 72 is made fast to the turntabletransversely thereof and the lower ends of the cylinders 66 are providedwith spaced lugs 73 for receiving ears projecting forwardly from the barand pivot pins 70. The free ends sheave 120 for rotation about an axisperpendicular to of the piston rods 74 which project from the upper endsof the cylinders are pivotally connected by pins 76 to the members 3838.Suitable connections 77 and 79 are provided at opposite ends of thecylinders through which hydraulic fluid may be forced or exhausted forthe purpose of positively elevating or depressing the ladder sections.The details of the hydraulic controls for effecting elevation anddepression are described in the aforementioned application and henceneed not be recounted herein.

Extension and retraction of the ladder sections is also effectedhydraulically and as shown in Figs. 1, 2 and 4 the hydraulic meansconsists of a cylinder and piston assembly 80 which includes a cylinder82 made fast to the lowermost ladder section from which projects apiston rod 84. Referring to Fig. 4, the lowermostladder section S1 isshown as having transverse cross braces 86, 88, 90, 92 and 94. Thecylinder 82 is fastened to theunderside of the section S1 by brackets 96and 98 mounted on the cross braces 88 and 90 with its longitudinal axisparallel to the center line of the ladder and with the piston rodextending toward the top 'of the section. At the lower endof thecylinder there projects a pair of spaced ears 100 which are formedintegral with the cylinder and between these ears is mounted a pair ofpulleys 102 and 104,

the axis of rotation of the pulleys being perpendicular to the plane ofthe ladder. The ears and pulleys constitute a multiple sheave pulleyblock and while shown as part of the cylinder casting. Alternatively theears 100 may be fastened to a bracket plate 101 (Fig; 3a) which in turnis fastened to the cross brace 88. At the free end of the piston rod 84there is made fast a multiple sheave pulley block 106 in which there aremounted two pair of sheaves, a first pair 108, 110 and a second pair112, 114. The axes of rotation of the sheaves 108, 110 are perpendicularto the plane of the ladder while the axes ofrotation of the sheaves 112,114 are parallel to the plane of the ladder. The cylinder is providedwith suitable hydraulic connections 116 and 118 at its opposite ends foreffecting movethe plane of the ladder. A sheave block 132 fast to thecross brace 94 carries the sheave 122 so that its axis is inclined tothe plane of the ladder. The inclination of theaxis of the sheave 122 tothe plane of the ladder is shown in Fig. 3. A pulley block 134 fast to across brace 92 carries the sheave 124 so that its axis is parallel tothe plane of the ladder. A multiple-pulley block 136 fast to theunderside of the cross brace 92,- carries the pair of sheaves 126, 128for rotation about axes parallel to the plane of the ladder as shown inFig. 3.

The ladder section S2 has sheaves 138 and 140 at its opposite ends madefast to cross braces 141 and 143 by pulley blocks 142' and 144respectively so that their axes are inclined to the plane of the ladder,the inclination being shown in Fig. 3.

The ladder section S3 carries no pulleys whatever but does have a crossbrace 146 for a purpose which will appear hereinafter.

The cable system for transmitting the motion or stroke of the piston rod84 to the ladder sections in such fashion as to cause extension andretraction consists of two cables C1 and C2 mounted on the sheavescarried by the cylinder and piston assembly and the various laddersections in the following fashion. One end of the cable C1 (Fig. 4) ismade connected at 148 to the lower end of the cylinder 82 or to thecross brace 88 by way of the bracket 96 (see Fig. 3a) and extends to theright therefrom about the sheave 108 carried by the block 106 andconstitutes a run r1 of the cable. The cable then passes around thesheave 108 and rearwardly, that is to the left as shown in Fig. 4 aboutthe sheave 102. at the base of the cylinder forming a second run 12.From the sheave 102 the cable passes forwardly, that is to the rightabout the sheave 110 forming a third run r3, about the sheave 110 andrearwardly, that is to the left to the sheave 104 forming a run r4. Theforegoing runs r1, r2, r3 and r4 constitute a part of the multiplyingportion of the cable. From the sheave 104 the cable passes forwardly tothe sheave 122 at the upper end of the lowermost ladder section forminga run 15 and then rearwardly to the left to the lower end of the laddersection S2 where it is connected at 150 to the cross brace 141 forming arun r6. A pair of guide rolls g-g mounted on the cross braces 90, 92near one side provide for holding the run r5 laterally displaced fromthe center line of the ladder so that it will not become fouled with themultiplying runs at the center line of the ladder. An integral extensionof the cable C1 or separate length thereof is also connected to thecross brace 141 at 152 and extends therefrom rearwardly about the sheave120 .on the ,lower end of the ladder section S1 forming a run r7. This.then passes about the sheave forwardly about thesheave 124 forming arun r8 from thence to the sheave128 forming a run r9 then about thesheave 112 forming a run r10 then about the sheave 126 forming a run r11then about the lower end of the ladder section S2'and then for wardlyand is connected at 158 tothelower cross brace 146 of laddersection'S3.' Either a continuation of this amass cable passing throug hthe brace I46 and made fastby clamps 145 ((see Figl3b) or aseparatelength-is con nected at 160 (Fig. 4) to the cross brace I46 ofthesection S3, extends forwardly-aboutthe sheave 140 on the ladder sectionS2 then-rearwardly and is connected at 16-2 to ladder section SI. I r

The important aspect of the present cable system is that its runs arecontained wholly within the extremities of the ladder sections and thatthe power cylinder for taking up and letting out cable is also containedwithin the systennso as to provide a compact space saving ar rangementof the cables and their operating mechanism for effecting extension andretraction of the ladder sec tions. Furthermore, the power cylinder ismovable in elevation and depression with the ladder sections hence thereis no change 'in the angle of pull exerted on the cable during elevationand depression. By locating the piston and cylinder assembly at thelower end of the lower ladder section and by' carryingthe" cable aboutthe cylinder the weight is kept at a low point hence keeping the centerof gravity of the equipment as low as possible. The arrangement of thecable about the sheaves on p the cylinder and piston assembly and on theladder sections is such as to give a proportion of approximately 7 to 1,that is for every foot of cable taken up the ladder. sections areextended seven feet. 1

The ladder section S2 travels faster than the pulley lock 108 preferablyat a ratio of about 4 to 1 so that the section S2 travels from itsretracted position to its fully extended position rapidly. The laddersection S3 may be of the same length as the section S2 and because ofthe arrangement of the pulley block its travel will be the same as thatof the section S2. 1

An important advantage of having the power cylinder contained within thecable system is that the effect of the extension of the piston rod isincreased by the length of the cylinder in contrast to prior powercylinders wherein the cable does not pass about the ends of thecylinder, the pulley block being made fast to the' piston rod and thecable having itsorigin at the piston rod end of the certain of thesheaves to wit 122, 138 and 140 were mounted so as to be inclined to theplane of the ladder sections and this was done for the purpose of havingthe runs transmitting the I motion to the section passing over thesesheaves located at opposite sides of the plane of the ladder and thus toneutralize the forces in the runs which would tend to bow the laddersections and hence to eliminate binding of the sections as they slidewithreference, to each other. by placing the sheaves as indicated thepull of the cable atone side of the extended, ladder is substantiallyneutralized by that of the 'other side of the extended ladder and hencethe forces at opposite sides are substantially balanced so that lightersections may be employed.

With the foregoing arrangement of cables when the piston rod 84 isextended the runs between the sheaves 102, 104 and 108 are extendedthereby taking up the runs between the sheaves 112, 114 and 126 and 128rapidly, causing ladder section S2 to move rapidly toward the top of theladder section. S1. Movement of ladder section S2 simultaneously etlectsmovement of the ladder section S3 toward its upper end through themedium of the cable system C2. The cables are so proportioned that thesections S2 and S3 reach their full extension substantially at the sametime.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

This application is a division of my Patent No. 2,614,743.

I claim:

I; An aerial extension ladder comprising a plurality of ladder sectionsslidably connected together, multiple.- sheave pulley blocks fast to thelowermostladder section at longitudinally spaced points, a powercylinder containing a piston and rod fast to the lowermost laddersection between said spaced multiple-sheave pulley blocks, amultiple-sheave pulley block fast to the protruding end of the pistonrod of the power cylinder and cable means having runs extending from thesheaves carried by the inultiple-sheave pulley block fast to the pistonrod to the sheaves carried by said spaced multiple-sheave pulley blocks,said cable means having ends connected to said lower ladder section withthat portion intermediate its ends entrained about and free to run onthe sheaves carried by said multiple-sheave pulley blocks, one run ofthe cable means extending about the sheaves on said spacedmultiple-sheave pulley blocks having a portion of it con izected to thelower end of the next ladder section, said power cylinder being operableto extend and retract the piston rod, extension of the rod moving themultiplesheave pulley block carried thereby away from one of said spacedmultiple-sheave pulley blocks and toward the other of saidmultiple-sheave pulley blocks and operating on the entrained cable meansso as simultaneously to increase the length of the runs between thesheaves carried by one of said spaced multiple-sheave pulley blocks andthe sheaves carried by the multiple-sheave pulley block fast to thepiston rod, and to decrease the length of the runs between the sheavescarried by the other of said spaced multiple-sheave pulley blocks andthe sheaves carried by the multiple-sheave pulley block fast to thepiston rod.

2. An aerial extension ladder according to claim 1, whereinthemultiple-sheave pulley block carried by the piston rod has twopairsof sheaves, one of the pair of said two pairs of sheaves carried by thepiston rod and the sheaves carried by the multiplesheave pulley block atthe lower endof the power cylinder being mounted to turn on axesparallel to each other and perpendicular to the plane of the laddersection and the other pair of said two pairs of sheaves carried by thepiston rod and the sheaves carried by the multiple-sheave pulley blockat the upper end of the power cylinder being mounted to turn on axesparallel to each other and parallel to the plane of the ladder section.

3. An aerial extension ladder according to claim 1, wherein thereareadditional single-sheave pulley blocks fast to the lowermost laddersection at longitudinally spaced points beyond the multiple-sheavepulley blocks, over the sheaves of which that portion of the cableconnected to the second ladder section is guided from the sheaves of thespaced multiple-sheave pulley blocks to said connector.

4'. An aerial extension ladder according to claim 1, wherein there areadditional single-sheave pulley blocks fast to the lowermost laddersection near the ends thereof beyond the spaced multiple-sheave pulleyblocks, over the sheaves of which the cable runs from said spacedmultiple-sheave pulley blocks, and is made fast to the second laddersection near its base, the sheave in the single-sheave pulley block atthe base of the lowermost ladder section being mounted to turn on anaxis per-' pendicular to the plane of the ladder and the sheave in thesingle-sheave pulley block near the top of the lowermost laddersectionbeing mountedto turn on an axis inclined to the plane of said laddersection, the axes of all of said sheaves being disposed lengthwise ofthe ladder section along a line substantially midway between its siderails and close to the midplane of the section.

5. An aerial extension ladder according to claim 1, wherein there arelongitudinally spaced single-sheave pulley blocks connected to the endportions of the second ladder section, and second cable means isconnected to the upper end of the lowermost ladder section and the lowerend of the uppermost ladder section and passes over the sheaves carriedby the spaced single-sheave pulley blocks connected to the ends of saidsecond ladder section.

6. An aerial extension ladder according to claim 1, wherein there arelongitudinally spaced single-sheave pulley blocks connected to the endportions of the second ladder section, and second cable means isconnected to the upper end of the lowermost ladder section and the lowerend of the uppermost ladder section and passes over the spaced sheavescarried by the spaced singlesheave pulley blocks, and that the sheavescarried by the single-sheave pulley blocks at the ends of the secondladder section are mounted to turn on axes parallel to each other andinclined to the plane of said second ladder section.

7. An aerial extension ladder comprising a plurality of ladder sectionsslidably connected together, first and second multiple-sheave pulleyblocks fast to the one lad.- der section at longitudinally spaced pointsnear the lower and upper ends respectively of said one ladder section, apower cylinder containing a piston and rod fast to said one laddersection between said spaced first and second multiple-sheave pulleyblocks, a third multiple-sheave pulley block fast to the piston rod ofthe power cylinder, first and second single-sheave pulley blocks fast tosaid one ladder section at longitudinally spaced points beyond the firstand second multiple-sheave pulley blocks, cable means having a portionconnected to said one ladder section near the first multiple-sheavepulley block at the lower end of the power cylinder, said cable meanspassing from said point of connection about one spaced pair and then theother spaced pair of sheaves carried respectively by the onemultiple-sheave pulley block at the lower end of the power cylinder andthe third multiple-sheave pulley block carried by the piston rod, fromsaid other spaced pair of sheaves to the single-sheave pulley block atthe upper end of said one ladder section, from there back to the lowerend of the next ladder section where it is connected to said next laddersection, from there to the single-sheave pulley block at the lower endof said one ladder section to the second multiple-sheave pulley block atthe upper end of said one section, about a third spaced pair andthen afourth spaced pair of sheaves carried respectively by saidsecondmultiple-sheave pulley block and said third multiple-sheave pulleyblock and from thence to an anchorage on said one ladder section nearthe second multiplesheave pulley block.

8. An aerial extension ladder according to claim 7,

wherein there is a single-sheave pulley block located ad-t jac'ent themultiple-sheave pulley block at the upper end of the ladder section forreceiving the run of the cable from the single-sheave pulley block atthe lower end of the section and guiding it to the sheaves carried bythe multiple-sheave pulley block at the upper end of the section.

9. An aerial extension ladder according to claim 7, wherein there areguide-rolls mounted on the ladder to turn on axes perpendicular to theplane of the ladder section, said guide-rolls being spaced laterally ofthe center line of the ladder section to guide the run of the cable fromthe multiple-sheave pulley block at the lower end of the cylinder to thesingle-sheave pulley block at the upper end of the section.

10. An aerial extension ladder comprising a plurality of sectionsslidably connected together, a power cylinder including a piston and rodprotruding therefrom connected to; the lowermost laddersection, saidcylinder and its piston rod being parallel to the center line of theladder section longitudinally spaced multiple-sheave pulley blocks fastto said lowermost ladder section, one at the lower end of the laddernear the lower end of the power cylinder and the other at the upper endof the ladder section, and a multiple-sheave pulley block carried by thepiston rod alternatively movable toward one and away from the other ofthe spaced multiple-sheave pulley blocks at the lower and upper ends ofthe ladder and a cable system mounted to run on the sheaves of saidmultiple-sheave pulley blocks, there being a first series of runsextending between the sheaves on the multiple-sheave pulley blockcarried by the piston rod and the sheaves carried by the multiple-sheavepulley block at the lower end of the ladder and a second seriesextending from the sheaves carried by the multiple-sheave pulley blockon the piston rod to the sheaves carried by the multiplesheave pulleyblock at the upper end of the ladder section, said first and second runsbeing alternatively lengthened and shortened by the movement of thepiston rod.

11. An aerial extension ladder comprising a plurality of sectionsslidably connected together, cable means and power operated meansconnected thereto for effecting extension and retraction of thesections, said cable means having motion transmitting portionsinterconnecting the ladder sections and a multiplying portion formultiplying the motion applied to the transmitting portion by the poweroperated means, said transmiting portions being disposed so that anequal number of runs of the cable means lie at opposite sides of theplane of each ladder section.

12. An aerial extension ladder comprising first, second and thirdsections slidably connected together, cable means and power operatedmeans connected thereto for efiecting extension and retraction of thesections, singlesheave pulleys mounted on the first and second laddersection near their opposite ends, said cable means having motiontransmitting runs interconnecting the ladder sections running on thesheaves of said single-sheave pulleys, multiple-sheave pulley blocksmounted on the first ladder section, a multiplying portion of the cablemeans running on the sheaves 'of said multiple-sheave pulleys formultiplying the motion applied to the transmitting portion by the poweroperated means, the sheaves of the pulleys near the ends of the firstand second sections being disposed so that the motion transmiting runslie at opposite sides of the planes of said first and second sections,and cable ends running from said second section to the lower end of thethird section and being connected thereto.

13. An aerial extension ladder according to claim 12, wherein thepulleys at the ends of the first and second ladder sections are inclinedto the plane of said sections so that the runs of the cable passing overthe sheaves will lie at equal distances at opposite sides of the planesof said sections.

References Cited in the file of this patent UNITED STATES PATENTS328,614 Reynolds Oct. 20, 1885 835,153 Cooper Nov. 6, 1906 1,866,801Ferris July 12, 1932 FOREIGN PATENTS 117,330 Germany Feb. 2, 1901

